Infliximab-induced hot kidneys on bone scintigraphy

^99mTechnetium-methylene diphosphonate bone scintigraphy is widely used in various clinical settings to detect bone abnormalities. Many reasons may cause abnormal tracer uptake in soft tissues on bone scintigraphy. Here, we present a 70-year-old man diagnosed with rheumatoid arthritis receiving chimeric anti-tumor necrosis factor alpha (TNF-α) therapy (infliximab). In order to evaluate the bone involvement of rheumatic disease, the patient underwent a whole-body bone scan that revealed left side dominant diffuse uptake in both kidneys defined as the "hot kidneys." Since the patient had no other identifiable reason, anti-TNF-α therapy might be responsible for the "hot kidneys" on bone scan. Thus, therapy regiment of the patient changed from the chimeric anti-TNF-α to a human monoclonal TNF inhibitor (golimumab). After 6 months of the change of the therapy, the bone scintigraphy was repeated and revealed that the previous "hot kidneys" finding had disappeared.